1. Field of the Invention
The present invention relates to a sensor for detecting a light spot position and to a displacement measuring device using the sensor.
2. Description of the Related Art
A sensor for detecting an incident position of a light spot can be configured using an existing image sensor such a CCD. Such a light spot position sensor is arranged on one of two members together with a light source for providing a light beam. The light beam output from the light source is reflected at the other of the two members and enters the light spot position sensor. It is theoretically possible to use an incident position of the light beam at this moment to detect a tilt or gap between the two members.
There is no actual example of a displacement measuring device that incorporates the above existing CCD. When CCD is incorporated into an encoder part of a small displacement measuring device, a restriction on size causes several disadvantages. For example, the displacement measuring device can not be down sized, shaped arbitrarily and sized to an arbitrary photosensitive pixel. In addition, it elevates the cost and is affected from an actual precision.